May, 1941. Amid the turmoil of the Blitz, the body of a St Paul's chorister is found in the cathedral crypt. Detective Chief Inspector Coburg and Sergeant Lampson face a delicate investigation within London's most cherished landmark. The dead man was far from popular, and the cathedral's wartime staff - Night Watch volunteers, clergy - and visitors offer no shortage of suspects. When the inquiry uncovers ties to Bletchley Park's secret operations and a murky trade in art and rare books, the mystery deepens. And when the killer strikes again, Coburg must act swiftly to preserve both justice and the sanctity of St Paul's.